Not sure if you're specifically trying to block out noise around you. I like to listen to music and audiobooks at work, but I need to be able to hear if someone comes over to ask a question. So I use one of those Plantonics Marque M165 Bluetooth ear pieces. It plays mono for the music (hated sitting with one ear bud unconnected and missing out on "half the music" from a stereo set). For audiobooks, who cares anyway, right?
The battery life is around 6 hours (says 7, but it'll start to nag you at the 6th hour and won't quit). And since I listen to my audiobooks and music on my phone, if the phone rings, I can answer it immediately without picking it up.
One more benefit - at least for me. People tend not to interrupt unless it's a real question because they think I might be on the phone.